A monthly injection of a long-acting version of naltrexone - a drug used to treat addiction - is a well-tolerated treatment for alcohol dependence and it can significantly reduce episodes of heavy drinking, according a new study.

“This marks a big step toward enhanced standard of care for 18 million people affected by alcohol dependence in this country - improving their health and day-to-day functioning in work and home lives,” Dr. James C. Garbutt, from the University of North Carolina at Chapel Hill, said in a statement.

In the 6-month study, 624 alcohol-dependent adults were randomly assigned to get a monthly injection of a low dose or high dose of long-acting naltrexone, or an inactive placebo. In addition, all of the subjects received 12 sessions of low-intensity psychosocial counseling.

As Garbutt’s group reports in this week’s Journal of the American Medical Association, treatment with the higher naltrexone dose reduced the number of heavy drinking days by 25 percent, compared with placebo. The low-dose injection cut the rate by 17 percent, which fell short of significance from a statistical standpoint.

Fourteen percent of subjects in the higher dose naltrexone group discontinued the drug because of adverse affects, as did 7 percent in the lower dose group and in the placebo group.

“The long-acting formulation has the potential to improve intervention strategies for alcohol dependence by providing a predictable pharmacological foundation for treatment,” the investigators conclude.

The study was funded by drug maker Alkermes, Inc., which markets long-acting naltrexone under the name Vivitrex.

SOURCDE: Journal of the American Medical Association, April 6, 2005.